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WIRELESS POWER TRANSMISSION SOLAR POWER SATELLITE (SPS) POWERING THE FUTURE

Energy can neither be created nor be destroyed. But it has a remarkable capability that can change its form from one form to another!!!

Contents INTRODUCTIONHISTORYWHY SPS ?DESIGNWIRELESS POWER TRANSMISSIONMICRO WAVE POWER TRANSMISSIONADVANTAGES COMPARISIONCONCLUSION

INTRODUCTION The new millennium has introduced increased pressure for finding new renewable energy sources.

Building a power station in space to transmit electricity to Earth by way of radio waves-the Solar Power Satellites.

Microwave Wireless Power Transmission.

SPS is a clean, large-scale, stable electric power source.

HISTORYPeter Glaser invented the concept of a large SPS in 1973

4The U.S Department of Energy (DOE) and the National Aeronautics and Space Administration (NASA) examined the SPS concept extensively during the late 1970s.

Fresh look Study, SPS Concept Definition Study during 1997 & 1998

SPS Exploratory and Research Technology.

DESIGNMainly consists of 3 Parts 1. collecting of solar power in space 2. transmitting power to earth 3.receiving power on earth

SUNLIGHT ELCTRICITYSolar energy conversion(solar photons to DC current)

a) photovoltaic conversion (PV) b) Concentrated photovoltaic conversion (CPV) c) Solar Dynamic conversion(SD)Energy paybackWorking life time

Wireless power transmission to the earth

transmissionThe 50Hz ac power tapped from grid line is stepped down to suitable voltage level for rectification in to dc.Then it is supplied to oscillator fed magnetron.Magnetron consist of electrons supplied by cathode which are collected by positively charged anode.The electrons are forced to move in a circular path by a high power permanent magnet.Electromagnetic radiation in microwave range is generated

MICROWAVE TRANSMISSION IN SPSThe conversion of direct power to microwave power.

The formation and control of microwave beam.

The collection of the microwave energy and its conversion into electrical energy at the earths surface.

The key microwave components in a WPT system are the transmitter, beam control and the receiving antenna called RECTENNA .TRANSMITTERThe key requirement of a transmitter is its ability to convert dc power to RF power efficiently and radiate the power to a controlled manner with low loss.

The transmitters efficiency drives the end-to-end efficiency as well as thermal management system.

The main components of a transmitter include dc-to-RF converter and transmitting antenna. The main dc-RF converter s are klystrons.

BEAM CONTROLA key system and safety aspect of WPT in its ability to control the power beam. Retro directive beam control systems have been the preferred method of achieving accurate beam pointing.

A coded pilot signal is emitted from the rectenna towards the SPS transmitter to provide a phase reference for forming and pointing the power beams.

RETRO DIRECTIVE BEAM CONTROL

RECTENNARectenna is the microwave to dc converting device .It is mainly composed of a receiving antenna and a rectifying circuit.Fig. shows schematic of Rectenna. It consists of a receiving antenna, an input low pass filter, a rectifying circuit and an output smoothing filter.In Rectenna arrays, the diode is the most critical component to achieve higher efficiencies because it is the main source of loss. Diode cut off frequency is given by =1/ [2RsCj], where is the cut off frequency, Rs is the diode series resistance, Cj is the zero-bias junction capacitance.

ADVANTAGESThe power could be directed to any point on the earths surface.

The power density would be uninterrupted by darkness, clouds, or precipitation, which are the problems encountered with earth based solar arrays.

The realization of the SPS concept holds great promises for solving energy crisis No moving parts.No fuel required.No waste product.

APPLICATIONSSolar power satellite (SPS) is the largest application of the WPT.The SPS concept arose because space has several major advantages over earth for the collection of solar power.There is no air in space, so the satellites would receive somewhat more intense sunlight, unaffected by weather.Another application of the WPT is moving targets such as fuel free airplanes, fuel free electric vehicles, moving robots and fuel free rockets.Microwave devices offer the highest efficiency of conversion between DC electricity and microwave radiative power.

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